Description:

Since using this AMD computer, including a Radeon 5500 XT graphics card, I noticed that the screen is (partly) flickering after suspending and resuming. Moving the mouse increases the flicker, raising a window (probably causing a repaint) restores that part of the screen to normal. Only after restarting the WM or setting a window to full screen and back, the flickering fully stops.

After upgrading my window manager a week ago, I also noticed distortions after resuming (see screenshot; the only thing I redacted was my email address in the taskbar). This made me think my window manager, IceWM, was at stake, and I reported this bug at their repository: https://github.com/bbidulock/icewm/issues/588

However, as they stated there, it was probably a bug in the X server. As suggested, I tried to disable the new GLAMOR driver by adding

Section "Device"
Identifier "nogpu"
Driver "modesetting"
Option "Accelmethod" "none"
EndSection

Section "Module"
Disable "glamoregl"
EndSection

to /etc/X11/xorg.conf.d/00-noglamoregl.conf. This solved the flickering and distortions after resuming, but now there was heavy tearing during scrolling, as if my compositor was disabled. What was worse, was that mpv couldn't find a graphics card anymore, or something like that:

[ffmpeg/video] h264_v4l2m2m: Could not find a valid device
[ffmpeg/video] h264_v4l2m2m: can't configure decoder

So I don't consider this a good solution (I'd rather live with repainting my screen every now and then, than not being able to play videos). At the said page, they also mentioned this commit <https://cgit.freedesktop.org/xorg/xserver/commit/?h=server-1.20-branch&id=1e3c5d614ee33d9eac1d2cf6366feeb8341fc0f4>, but I'm not sure if that one is already within Arch Linux' xorg-server and/or it really solves this issue.

Additional info:
* xorg-server 1.20.11-1
* icewm 2.3.4-1
* picom 8.2-1

Enclosed is Xorg.0.log, which shows an error at 4096.430, when I tried to resume my monitor by switching it on and pressing a key. However, that failed indeed (it seems the DisplayPort handshake fails every now and then), so I switch to VT-3 and back to 7 to restore my screen. At that instance, this issue didn't pop up.

I'd rather look at later moments, but the only error output then is a timing problem, complaining my system is too slow (which is silly, because I have 8 core/16 threads at about 2.2 GHz :).